Soldering Surprise

Richard Grugel, a materials scientist at the Marshall Space Flight Center, watched his video monitor in disbelief. A transmission from the International Space Station was playing. The scene: Astronaut Mike Fincke touches the tip of a soldering iron to a wire wrapped with rosin-core solder. The solder, heated, became a molten blob with a droplet of rosin clinging tight to the outside. Solder melts: that’s not too surprising. It’s the behavior of the rosin that amazed. As the temperature increased, the droplet began to spin, round and round, faster and faster, like a miniature carnival ride.